In Spring, the Validator interface is used for custom validation logic on objects, typically before saving them to a database or processing …

Spring Web Request Lifecycle — describes the sequence of steps an HTTP request goes through in a Spring (Boot) application from arrival …

Spring Caching — a framework feature that allows you to store method results in cache to improve performance and reduce database or …

@JsonIgnore — a Jackson annotation used to exclude a field or method from JSON serialization or deserialization. 🧩 Purpose Prevents sensitive or …

@SpringBootTest — used to load the entire Spring application context for integration testing in Spring Boot. 🧩 Purpose It allows you to …

@PreFilter & @PostFilter are Spring Security annotations used to filter collections or arrays before or after a method executes — based on …

Spring Security ContextThe SecurityContext in Spring Security holds the authentication and security-related details (like the logged-in user, roles, etc.) for the current …

🔹 1️⃣ String.trim() The classic method for removing whitespace from both ends of a string. Syntax: Behavior: ✅ Example: Output: 🔹 2️⃣ …

🔹 1️⃣ What Is a Static Block? A static block (also called a static initializer) is a block of code inside a …

In Java, asynchronous methods are methods that start a task and return immediately, allowing the program to continue executing without waiting for …

Sorting a list of strings in Java is straightforward — and you can do it in several ways, depending on whether you …

In Java, the volatile keyword is used to indicate that a variable’s value may be changed by multiple threads, and that all …

In JUnit (Java Unit Testing framework), annotations are special markers (prefixed with @) that tell JUnit how to run and organize your …

🧠 What is EXISTS? EXISTS is a logical operator in SQL that checks whether a subquery returns any rows. It’s often used …

Here’s a comprehensive guide to Docker container commands with explanations and examples. I’ll organize them by category so it’s easy to reference. …

Here’s a comprehensive list of Docker commands related to images, broken down by category, with explanations and examples: 1. Pulling and Searching …

A Secret in Kubernetes is an object that stores sensitive information such as passwords, tokens, SSH keys, or certificates, separate from application …

A ConfigMap in Kubernetes is an API object used to store non-confidential configuration data in key-value pairs, so you can separate configuration …

A Kubernetes Ingress is an API object that manages external access to Services, typically HTTP and HTTPS traffic, providing routing, load balancing, …

A Service in Kubernetes is an abstraction that defines a stable network endpoint for accessing a set of Pods — even if …

A Deployment in Kubernetes is a higher-level controller that manages ReplicaSets and provides declarative updates for Pods and applications. In simpler terms …

A ReplicaSet (RS) in Kubernetes ensures that a specified number of identical Pods are running at any given time.It’s one of the …

A Pod is the smallest and simplest deployable unit in Kubernetes. It represents one or more containers that share the same network, …

🧱 1. Repository Setup Purpose: Start tracking a project with Git. Command Description Example git init Initialize a new Git repository in …

Let’s break down the difference between CrudRepository, PagingAndSortingRepository, and JpaRepository clearly — because they are related but not identical. 🧩 1. Common …

⚙️ 2. Creating Classes A class is a blueprint for creating objects. ✅ The constructor() runs automatically when you create a new …

🧩 1. What Is Destructuring? Destructuring means “unpacking” values from arrays or properties from objects into distinct variables. Instead of doing this: …

🧩 1. What Is Optional Chaining? Optional chaining (?.) lets you safely access nested object propertieswithout causing an error if something in …

Let’s go step-by-step through the Spread (...) and Rest (...) operators in modern JavaScript. 👇 🧠 What They Are Both use the …

In Vue 3, this concept is expressed using the createApp() function — it’s how you initialize and mount your application. 🧩 What …